Nutrition for a Better Night's Sleep
Sleep plays a key role in our overall wellbeing, including our physical and mental health. It is during the night when our brains store and process the day's information, our cells get repaired and our body gets rid of toxins.
From a weight management perspective, research has found that having an insufficient sleep duration and poor quality sleep is linked to the risk of weight gain and obesity, insulin resistance and type 2 diabetes. This is due to increased food intake, decreased energy expenditure and changes in levels of appetite-regulating hormones.
We can work on improving our bedtime routine by limiting our screen time before going to bed or meditating before sleep. But can our diet help us fall asleep faster or have a better quality night's sleep during the night or prevent us from feeling refreshed in the morning? Let's find out...
Before we dive in to sleep nutrition we need to understand what regulates our sleep.
Biological clocks (or circadian clocks) are the body's natural timing devices. They produce and regulate circadian rhythms which are physiological, psychological and behavioural changes in the body following a cycle of about 24 hours. These changes include blood pressure, body temperature, hormone levels, the number of immune cells in blood, and the sleep-wake cycle.
Circadian rhythms regulate the production and release of two very important hormones: MELATONIN - 'sleep hormone', which prepares you for sleep and CORTISOL - 'wake hormone', which prepares you to wake up.
Levels of melatonin peak during the night and are lowest in the morning, whereas levels of cortisol are other way round. It's the higher level of cortisol that helps us wake up in the morning.
With that in mind, let's look how certain nutrients can support the production of melatonin and therefore support sleep.
What can promote a good night's sleep?
Tryptophan is a precursor to melatonin (sleep hormone), therefore consuming tryptophan-rich foods can help to reduce sleep onset latency, so we can fall asleep faster.
Tryptophan can be found in foods like:
- Whey protein
- Sesame seeds
Carbohydrates, still demonised by many, can actually help us fall asleep faster and sleep more deeply, but before you order that pizza or take a bit of that cake thinking "I will sleep like a baby tonight", I'm talking here about digestible carbohydrates. These can be found in foods like starches from potatoes, rice, pasta and whole grains.
Digestible carbohydrates increase the availability of tryptophan in the brain and as a result increases the rate at which tryptophan can be used to make melatonin.
Studies suggest that eating a digestible carbohydrate-rich meal 2-4 hours before bed may help us fall asleep faster (shortening sleep latency) and sleep more deeply throughout the night (improving sleep quality).
Our bodies can make their own melatonin, however we can also find it in certain foods that have sedative effect. These include:
Animal products - eggs, fish and milk
Plant foods - nuts (almonds), some cereal (oats, barley, wheat), vegetables (tomatoes, peppers, mushrooms), legumes (beans, lentils), berries (tart cherries), seeds, and oils (extra virgin olive oil, linseed oil, soybean oil)
Certain B vitamins (B1, B3, B6, B9, B12) also enable us to fall asleep faster and get a good night's rest. This is because they are involved in the production and use of melatonin and other sleep neurotransmitters. Even a mild deficiency in any of these five B vitamins is associated with poorer sleep.
So, where can we find those B vitamins?
B1 - corn flour, black beans, enriched cereals and pasta, hazelnuts and soybeans
B3 - fresh tuna, peanuts, turkey, chicken, salmon and portobello mushrooms
B6 - raw garlic, sunflower seeds, turkey and potatoes
B9 - soybeans, dark green leafy vegetables (turnip greens, spinach, romaine lettuce, asparagus, Brussels sprouts, broccoli), beans, lentils, nuts and seeds, wholegrains, liver, seafood, eggs
B12 - oysters, oily fish, poultry meat, eggs and dairy. Vegans may need to supplement this vitamin as it's mostly present in animal products
Magnesium is not only good for relaxing our muscles but it also enhances the secretion of melatonin and promoting sleep as a result. Low levels of magnesium may make it difficult for us to fall asleep and could even lead to insomnia.
Top food sources of magnesium include:
- Shell hemp hearts
- Sesame seeds
- Pumpkin seeds
- Sunflower seeds
- Dried thyme
It should be noted however, that the process of digesting complex foods containing magnesium takes longer than a magnesium supplement and so does its absorption into the bloodstream, therefore it's important to factor in that time.
Studies that test magnesium for sleep usually use supplements containing between 250 to 500 milligrams of magnesium about an hour or 30 minutes before bed and often combined with another mineral supplement like zinc or calcium.
Zinc has slightly different effects when it comes to sleep - it helps with the quality and duration of sleep.
Some good sources of zinc include:
- Sesame seeds
What can hinder our sleep?
So, now that we know about foods which can support the production of melatonin. But what about factors that can prevent us from having a good night's sleep?
Several studies found that sugar (in particular added sugar in commercial foods and drinks) leads to disturbed sleep patterns, more restlessness during sleep and shorter uninterrupted sleep.
We all know that drinking water is good for us for many reasons, this also includes sleep quality. However, too many liquids before bed can actually reduce the length of our uninterrupted sleep as we might need to wake up to urinate (a condition called Nocturia). Therefore, it is best to maintain hydration levels throughout the day and limit the fluid intake before bedtime.
Alcohol is a sleep-inducing substance so it can help you fall asleep as soon as your head touches the pillow and you might sleep more deeply during the first part of the night. However, as the night progresses, the sleep is more disrupted and the amount of time you spend in the deep sleep is decreased. This will cause you to feel tired in the morning, less productive during the day and crave sugary snacks to help you get through the day. Additionally, alcohol may act as a diuretic and you might end up waking up at night to empty your bladder.
Who doesn't like a cup of coffee first thing in the morning, maybe even a second cup mid-morning. Third? Forth? Fifth? Studies suggest that 400mg of caffeine 6 hours before bed can delay sleep by 1 hour. It takes about 5 hours for half of the caffeine consumed to leave the body, however, depending on the individual, it can be between 1.5 and 9.5 hours! This is why caffeine may affect sleep, even if consumed 6 hours before bedtime.
Some obvious sources of caffeine include coffee, black and green tea, coca cola, energy drinks and some sports drinks. There are some less obvious foods that also contain caffeine like: dark chocolate (the darker the chocolate higher its caffeine content), milk chocolate, some cookies, sweets and exercise bars.
Sudden dietary changes
Abrupt changes in the amount of calories or macronutrients (protein, carbohydrates, fats) proportions eaten may make it harder to fall asleep or may disrupt the quality of sleep, particularly in the first few days.
Eating late vs. Sleep
Late night eaters
Eating late at night might not necessarily mean that we will sleep poorly. Meal times and sleep quality depends on whether we are early birds or night owls. For example, if night owls eats dinner no later than 6pm then they might have problems falling asleep due to going to bed hungry. However, having dinner early might work for early birds.